Sorry, I didn't see this until just today, so you may miss this, but in my case I had a stroke due to an up to then unknown hole between the atria of my heart.

Sorry, I didn't see this until just today, so you may miss this, but in my case I had a stroke due to an up to then unknown hole between the atria of my heart. I needed to keep my heart rate and blood pressure down prior to a repair procedure, so I had to give up caffeine (among many other things, like walking up hills!)